Our appeal, in which we have argued that users are not “charged” in any way, nor that it is possible to “buy” anything in GfxTablet (because donations do not change the functionality), has been rejected:

After review, your app GfxTablet (at.bitfire.gfxtablet) has been administratively rejected pending verification of your organization’s charity status. Donations may only be collected within an app under certain conditions:

Donations are only permitted for validated non-profit charitable organizations (for example, a validated 501(3) charitable organization or the local equivalent).

Donations must be facilitated via a web browser, and any collection must be made through a secure payment system.

If you belong to an eligible charitable organization, please follow these steps:

Attach a copy of your organization’s IRS determination letter or other acceptable proof in your reply to this notification. The provided information must indicate your status as a charitable organization.

Alternatively, if you are not a charitable organization, you must remove the donation functionality from your app [highlighting by Google], or accept payment through Google Play’s in-app billing service or Paid app distribution on the Play Store. You can learn more about in-app billing in our Help Center:http://developer.android.com/google/play/billing/index.html

Once the issue has been resolved, please resubmit your app for review.

Note that all of these conditions need to be fulfilled for us to reinstate your app.

Because we’re neither a charity organization (although we make open-source), nor do we have the time and desire to fiddle around in GfxTablet because of Google’s demands, nor are we greedy for 1* ratings, please use the alternative download locations mentioned on the GfxTablet homepage.

I think google just wants all types of purchase (including donations) to be applied through in app purchases, or not included at all. A large amount of the apps I install have links that say “donate a beer” or “donate a cup of coffee” but they all seem to go through the playstore as in app purchases. I guess it’s just a security thing that they have to send out to every app, because there will be some people out there that will try and steal users money through phishing links. Security is a very important thing.

I guess it’s just a security thing that they have to send out to every app

They didn’t just send out something, but they have removed GfxTablet from Play Store.

because there will be some people out there that will try and steal users money through phishing links. Security is a very important thing.

I guess it’s because they like to bind users and developers to Google Play, so that people will always have to use proprietary Google services (like in-app payment) when they want to use (otherwise open-source) Android. So,

apps can’t be sold in other app stores anymore (because the payments are bound to Google), and